The present invention generally relates to an apparatus and a method for installing a preform onto a mold surface, and more particularly to an improved apparatus and method for installing a preform onto a contoured mold surface via a roller device having a selectable roller skate to apply pressure thereon.
The installation of preforms onto a specified mold surface to form composite materials is well known in commercial and military applications. The resulting composite materials are desirable due to their mechanical characteristics such as a high strength to weight ratio and high thermal tolerances. As such, the preforms and the corresponding mold surfaces are essential initial components in the resulting composite materials that are frequently used to build structural supports, such as ducts for aircrafts.
Because of their advantageous mechanical characteristics, composite parts are proving to be increasingly valuable in serving as structural components in a variety of articles. Generally, in order to manufacture such parts, the preforms are “laid up” over a mold surface and then cured under elevated temperature and pressure. More specifically, because the resulting composite parts are oftentimes used in the aerospace or aircraft industries, the parts must be meticulously detailed as to their structural integrity. To meet these meticulous specification details, precise control of temperature and pressure conditions is required when the preform is cured on the mold surface.
The preforms may primarily be classified into two different types, namely, “prepregs” and “non-prepregs.” Prepreg preforms are generally sheets of fiber that have uncured resin embedded therein and are widely utilized for forming structure composite parts. Similar to the above, the prepreg preforms may be laid over the mold surface, and while being-maintained in position against the mold, it is subjected to heat and pressure to cure the prepreg preforms into the composite materials. Various apparatus may be utilized in maintaining the prepreg preforms in contact with the mold surface during the cure thereof such as press platens, vacuum bags or trapped rubber molding systems.
The other types of preforms are non-prepreg preforms. The non-prepreg preforms are generally similar to the prepreg preforms in that they are still laid up on a mold surface. However, unlike the prepreg preforms, the non-prepreg preforms are initially resin free. The lay up is subsequently vacuum bagged, and a vacuum is drawn from between the bag and mold surface such that the lay-up is compressed to atmosphere against the mold surface. However, in this process, resin is simultaneously drawn in through an inlet port in the vacuum bag and through the lay-up impregnating it. Finally, the now impregnated non-prepreg preforms are heated until the resin is cured.
Regardless of using processes that include prepreg preforms or not, one factor remains constant. The fibers, namely, preforms that subsequently form the composite parts, must be laid over the mold surface prior to being subjected to the above-specified processes. More specifically, whether the process involves prepregs or not, the fibers, or the preforms, must be initially laid over the mold and go through similar preparations in order to be ready for the above-specified processes.
The initial preparations needed for the preforms to be subsequently cured frequently involve manual labor. In the industry that values time-efficiency, precision and cost-effectiveness, the current preparations of preforms may oftentimes compromise such objectives.
For example, one such method now used of preparing the preforms is to lay-up individual preforms by hand. Thereafter, the preform may be installed to the mold surface using overhead infrared heat. Such method may result in long cycle times of several days. Furthermore, due to the lengthy cycle time, the profits in a given project that utilizes such method may be reduced from its projected optimal range.
More importantly, however, the lay-up of the preform upon the mold may be inappropriately accomplished because the manual approach of the current method lacks systematic uniformity, and thus compromising the requisite precision at times. Therefore, in the industry where such composite parts are often mass-produced, the inapt preparations just described may prove to have undesired effects upon the overall manufacturing of the composite parts.
Thus, there has long been a need in the industry, and in the aerospace industry in particular, for an apparatus and method for improving the lay-up of the preform upon the mold in a more time-efficient and cost-effective manner. In particular, there is a need to install the preform upon the mold by utilizing a systematic approach to consistently yield the requisite precision that the manual labor is unfit to provide.
The present invention addresses and overcomes the above-described deficiency of prior art lay-up processes by providing an apparatus and method that utilizes a roller device to apply selected pressure on the mold surface having the preform laid thereupon. More specifically, the roller device is sized and configured to engage at least one selected roller skate from a library of roller skates to apply the pressure corresponding thereto on the mold surface. In addition, the selected roller skate is further conformed to move along the contour of the mold so as to facilitate application of the desired pressure. In this respect, not only does the present invention mitigate the need to resort to inefficient and costly preparations, but it also maximizes the consistent precision that is often required in such processes.